This invention relates to a portable, hand-held depth indicator of the type generally used by dentists to measure the depths of the gingival sulci. The gingival sulci are the spaces between the gingival tissues (gums) and the teeth. The depth of each gingival sulcus is measured from the margin of the gingiva (top of the gum) to the epithelial attachment (point where the gum attaches to the tooth). With the two most common diseases of the gums and teeth supporting structures, gingivitis (inflamation of the gums) and advanced periodontal disease (sometimes called pyorrhea), the gums become swollen and begin to stand away from the teeth. If not treated early enough, the gums may actually withdraw from the teeth, forming pockets which may become filled with bacteria and pus, and result in the eventual destruction of the attachment of the teeth to the supporting bone structure. Advanced periodontal disease has been estimated to cause more adult tooth loss then the more common dental caries (cavities).
The most effective protection against gingivitis and advanced periodontal disease is early detection of any change in the gingival sulci by the periodical measurement and recordation of the sulcus depths at various locations around each tooth. A common instrument often used for this purpose is a depth probe, similar to that disclosed in Ward U.S. Pat. No. 3,058,225, comprising a handle with a fixed protruding sheath and a cylindrical probe tip extendable through the sheath and attached either directly to a mechanical indicator or indirectly, via electrical circuitry, to a current indicating device located on the probe handle. The major disadvantage with this conventional type of probe is that, to measure a sulcus depth, the sheath is rested on the margin of the gingiva while the probe tip is extended into the sulcus until it reaches the epithelial attachment. With such a probe the probe tip is not visible to the dentist as it is extended into the sulci and, if extended too far, may inadvertently penetrate or tear the epithelial attachment. In addition, since the depth measurement is indicated on the probe handle itself, the dentist must either measure and then record the individual measurements himself by hand, or employ an assistant to do the recording as the dentist calls out the measurements. Also, with the indicator on the handle itself, it is sometimes awkward or impossible, depending upon the location of the sulcus being measured, to read and record the measurement without removing the probe from the patient's mouth, thereby risking a disturbance of the measurement and a resulting erroneous reading. Since the normal mouth has from twenty-eight to thirty-two teeth and each tooth requires approximately six measurements, the time wasted by the separate measurement and recordation of each sulcus depth is considerable. Even if the electrical current indicating device is removed from the probe handle and placed where it can be more easily read, as suggested by Ward, the dentist must still stop and record each individual measurement himself or employ an assistant to do so.